Re: [Teep] [Last-Call] Artart last call review of draft-ietf-teep-architecture-16

[Mingliang Pei <[e-mail]>]

Hi Russ,

Great, thank you. Please see inline. I will update RFC with the two points
agreed.

Best,

Ming


On Thu, Apr 7, 2022 at 12:31 PM Russ Housley <[e-mail]> wrote:

> Please see below.
>
> On Apr 6, 2022, at 8:54 PM, Mingliang Pei <
> mingliang.pei=[e-mail]> wrote:
>
> Thanks Russ for your comments. Thanks Hannes for the PR. I made a minor
> comment on the PR. The changes look good overall.
>
> Please see my comments inline about "trust anchor" and "app store".
>
> Best,
>
> Ming
>
> On Mon, Mar 28, 2022 at 11:06 PM Hannes Tschofenig <
> [e-mail]> wrote:
>
>> Hi Russ,
>>
>> Thanks for the review.
>>
>> I have created a few PR based on your comments:
>> https://github.com/ietf-teep/architecture/pull/234
>>
>> I have added a few remarks below (mainly agreeing with your observations).
>>
>> Ciao
>> Hannes
>>
>>
>> -----Original Message-----
>> From: Russ Housley via Datatracker <[e-mail]>
>> Sent: Tuesday, March 29, 2022 12:08 AM
>> To: [e-mail]
>> Cc: [e-mail]; [e-mail];
>> [e-mail]
>> Subject: Artart last call review of draft-ietf-teep-architecture-16
>>
>> Reviewer: Russ Housley
>> Review result: Almost Ready
>>
>> I am the assigned ARTART reviewer for this Internet-Draft.
>>
>> Document: draft-ietf-teep-architecture-16
>> Reviewer: Russ Housley
>> Review Date: 2022-03-28
>> IETF LC End Date: 2022-04-07
>> IESG Telechat date: unknown
>>
>> Summary: Almost Ready
>>
>> Major Concerns: None.
>>
>>
>> Minor Concerns:
>>
>> Section 3.3 says:
>>
>>    Weak security in Internet of Things (IoT) devices has been posing
>>    threats to critical infrastructure that relies upon such devices.
>>
>> I'm a bit confused by this opening sentence.  IoT devices usually depend
>> upon an infrastructure.  This seems to be talking about an infrastructure
>> that depends upon a collection of IoT devices.  I suggest a minor edits to
>> help the reader understand that this sentence is not talking about network
>> infrastructure.
>>
>> [Hannes] I have changed the sentence to improve the wording.
>>
>> Section 9.3 says that a compromised REE "might drop or delay messages".
>> This discussion should be expanded to include the replay of messages.
>>
>> [Hannes] Agree.
>>
>> Section 9.4 says:
>>
>>    A root CA for TAM certificates might get compromised or its
>>    certificate might expire, or a Trust Anchor other than a root CA
>>    certificate may also expire or be compromised.
>>
>> I do not understand the difference between a Root CA and a Trust Anchor.
>> These are usually used a synonyms.  Please explain the difference that in
>> intended here.
>>
>> [Hannes] Good point. I removed part of the sentence.
>>
>>
> [Ming] Trust Anchor definition says "The Trust Anchor may be a
> certificate or it may be a raw public key.". When it is a certificate, it
> doesn't have to be the root certificate. It could be an issuing CA while it
> isn't a common practice. Do we limit it to a self-signed root CA? I am fine
> with this, and update accordingly.
>
>
> I think the point about not a "Root Certificate" in all situations is very
> helpful.  Please add that to the document.
>
>
Ming: will add a clarification line in the definition of "Trust Anchor"
that a "A Trust Anchor can be a non-root certificate when it is a
certificate.", and keep the original statement above.

>
>
>> Nits:
>>
>> Section 1 says:
>>
>>    ... The problems in the bullets above, on the
>>    other hand, require a new protocol, i.e., the TEEP protocol, for TEEs
>>    that can install and enumerate TAs in a TEE-secured location and
>>    where another domain-specific protocol standard (e.g., [GSMA],
>>    [OTRP]) that meets the needs is not already in use.
>>
>> Recommend breaking this long sentence up into at least two sentences.
>> There are two points.  First, the need for a protocol to address the
>> items listed earlier.  Second, where an existing domain-specific protocol
>> does not already exist, a new more general protocol is needed.
>>
>> [Hannes] Splitting the sentence improves readability.
>>
>> Section 4.4 says:
>>
>>    ... Implementations must support encryption of
>>    such Personalization Data to preserve the confidentiality of
>>    potentially sensitive data contained within it, and must support
>>    integrity protection of the Personalization Data.
>>
>> Why not say that implementation must support mechanisms for the
>> confidentiality and integrity protection of such Personalization Data?
>> Also, it seems like draft-ietf-suit-firmware-encryption offers one
>> mechanism for such protection.  Should it be referenced here?
>>
>> [Hannes] Agree that the sentence should be simplified. You are also right
>> by saying that a solution is available. I am not sure we should reference
>> the solution in this document or in the protocol spec.
>>
>> Section 4: Is an "App Store" a place where apps are stored, or is it a
>> place where apps a purchased?  The term seems to be used both ways, and in
>> one place, the document is very general by saying, "an app store or other
>> app repository".  Elsewhere, the term "Trust Anchor Store" is clearly a
>> place for storage of trust anchors.
>>
>> [Hannes] I am not entirely sure what do about this one. I hope for input
>> from my co-authors.
>>
>>
> [Ming] "app store" intends to mean "where apps are stored and can be
> acquired (such as Apple App Store / Google Play)". "Trust Anchor Store"
> means some storage within a device to keep a list of Trust Anchors. How
> about add a definition of "App Store" that was depicted in the diagram
> under Section "Entity Relations" to say the following?
>
>
> Definitions would resolve this comment.
>
>
Ming: thanks

>
> App Store: a service provider where an Untrusted Application may be
> downloaded.
>
>
> Suggestion: App Store: an online location from which Untrusted
> Applications can be downloaded.
>

Ming: looks better. I will use your version.


>
> Section 9.7: Please consider changing the section title to be something
>> like: "TEE Certificate Expiry and Renewal".  There is an earlier section
>> that talks about expiration of Root CA certificates.
>>
>> [Hannes] Makes sense.
>>
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